AGRICULTURAL RESEARCH
Year:2008 | Volume:8 | Issue:1 (A)|Papers Count:22

An experiment was conducted in farm condition to study the effect of different planting dates and genestine concentrations on nodulation and nitrogen fixation of three medicgo species for two years, (2004 - 2005). Three medicago species, in clouding Medicago polymorpha, Mradiata, Mrigdulawhich are suitable for cold and temperate zone were used. Planting dates on three levels, 20th of Feb, first and, 10th of March was considered as main plot, the medicago species as sub plot and genestine concentration in 2 levels of 0 and 20 Micromole/Liter in secondary plot considered as sub plot. The experiment performed with four replications in split -split- plot base on the complete randomized blocks design. The result showed that at first year, in accordance with more suitable temperature at the beginning of growing season, the medicago species had better growth, nodulation and nitrogen fixation than the second year which unsuitable temperature at the beginning of growing season was more long. The result in according to nodulation, nitrogen fixation and all other searchable characteristics have significant difference and M. polymorpha has better ability in nitrogen fixation and is better from the point of nodulation, nitrogen fixation, nitrogen percent and quantity of dry maters of root than other species. On third planting date, because of favorite air and soil temperature, nodulation and nitrogen fixation was at highest level in Medicago species, but in first planting date measure of nodulation and nitrogen fixation was at the lowest level in Medicago species because of the bad effect of low temperature of air and soil on growing, nodulation and nitrogen fixation. The use of genestion has a significant improving effect on nodulation and nitrogen fixation in medicago species. It represents the moderating mark of genestine and its role in declining the negative effect of low environmental temperature on nodulation and nitrogen fixation of medicago species. The study of corresponding effects of care and attendance showed that the use of genestine in the first planting date on all species under test causes the goosing rate in nodulation and nitrogen fixation. It represents the effect of genestine to make the plant withstanding toward cold for improving nodulation and nitrogen fixation of medicago species in farming conditions.

Drought as one the most important natural disasters directly affects the societies by water availability variations. It imposes a lot of economic, social and environmental costs and it's effects are increasing, unexpectedly. According to this phenomena extraordinary effects and changing the approach of crisis managing to risk management. We use standardized precipitation index (SPI) for monitoring different kinds of drought in great khorasan region. The results were applied for severity determination, relative comparing effects of drought, determining the credit ratio and the credit paying preferences in agricultural and water resources sectors. The results showed that the trends for drought variations are different during the months of year in the study regions. Additionally, the trends of SPI variations were different in various time scales for the same region. Considering the results of drought severity for the first six-month of 2002 show that the most severity of different droughts have been occurred in Gonabad with relative severity of 47. Therefore, this event requires 12.9% of credits relatively, with first order of preferences. Whereas, Bojnord city is with the least relative severity drought of 4, and the last credit paying preference, has relatively received 1.1% of province total credits.

Among the essential elements for potao (Solanum tuberosum L.) crop growth, nitrogen has more important role in leaf area increment, shoots growth rate and tuber yield. Therefore, to determine the time and value of supplemental nitrogen fertilizer in different stages of potato crop growth, it is required to use a reliable method to assess the uptakable nitrogen of soil during growing season. Therefore, in order to use chlorophyll meter to identify the required appropriate time of potato crop to nitrogen fertilizer and increment of nitrogen use efficiency, an experiment was conducted based on randomized complete blocks design with three replications in research farm of Ferdowsi University, College of Agriculture. Nitrogen top dress fertilizer was applied in two levels of 100 and 150 kgN.ha-1 and in two nitrogen index of 90 and 95 percent. The results indicated that 95 percent nitrogen index versus 90 percent nitrogen index performs a better efficiency in increment of potato crop yield. However, in 95 percent index, nitrogen fertilizer levels of 100 and 150 kgN.ha-1 did not showed significant difference in tuber yield. Nitrogen indices and nitrogen fertilizer levels did not perform significant effect on number of main stems and number of tubers in plant. The percentages of medium and large tubers were increased when the nitrogen fertilizer level was increased. Potato producers should apply nitrogen fertilizer to improve their yield but in time and sufficient application of nitrogen fertilizer requires an economic and fast procedure. It seems that application of nitrogen fertilizer by using chlorophyll meter, in addition to make desirable yield of tuber, reduce the nitrogen fertilizers level.

Strawberry is an important crop in fruit production, with a very short shelf life. In this study, the effect of pre-harvest calcium chloride application on the improvement of shelf life and some quality characters of Kurdistan cultivar were investigated. Foliar application of CaCl2 was done at different time courses (once, twice & thrice) with zero, 0.3 and 0.5 percentages (w/v). At harvesting time, fruits were picked and selected for uniformity of size and color (75% redness). Two and three times of foliar application of CaCl2 with zero, 0.3 and 0.5 percentages (w/v) decreased significantly fruit decay and increased the fruit shelf life. Foliar application of CaCl2 had little effect on other fruit quality characters. Also interaction between CaCl2 concentration and different foliar application on fruit calcium content and fruit decay in 4th and 11th days were significant but their effects on other characters were not significant.

Garlic Moth Dyspessa ulula Sch is one of the most important pests damaging crop both in store and in the field. Chemical pesticides are not suitable to control of this pest. So, study the other methods of control seems to be necessary. The effect of harvesting time on preventing garlic moth infestation was studied. Five different harvesting times including 11 June, 20 June, 30 June, 11 July and 21 July were considered for the experiments. This study was conducted in random block design with 4 replications. In this survey first and second harvesting dates were based on the time before the female ovipositing. The effects of each harvesting time on yield, storage capability and garlic moth infestation were studied. The results showed that, the yield was high at first and second harvesting time. There was no difference between the treatments in terms of storage capability. So, changing the harvesting date was not only reduced storage capability, but also controlled the garlic moth infestation.

In this research germination potential and yield of microtuber on two potato cultivars (Agria and Marfona) with three diameter size (<5, 5-10 and >10 millimeter) and three dormancy periods (3, 4 and 5 months) were investigated. Trial was a factorial based on RCBD design, with three replications. Percentage of germinated and non-germinated nicrotubers, weight, number and diameter of minitubers were recorded. A positive and significant correlation was observed between microtuber diameter and germination percentage. The higher size of microtuber was associated with more tuber yield. Results showed that cv. Marfona with 56.37% germination had greater yield than Agria (with 48.87%). Although in term of other parameters, Agria showed superiority. Amongst cultivars under studying, microtubers with greater diameter and longer dormancy period showed superiority for minituber weight, number and diameter. In this research, the interaction effects between treatments for majority of parameters related to yield was significant.

Knowledge improvement about seed germination response to soil moisture and temperature in order to determine the best times for sowing date is important, unfortunately information about seed germination response of chickpea to temperature, drought stress and their interactions are limited, So the main objectives of this experiment were quantifying seed germination response and predicting of cardinal temperatures, physiological days and thermal time requirement for seed germination in chickpea. To this, a split plot factorial experiment based on a completely randomized design with 6 chickpea genotypes (MCC.361, MCC.951, MCC.180, MCC.873, MCC.13 and MCC.463) and a range of temperatures (3, 5, 10, 15, 20, 25, 30 and 35oC) and drought stress levels (0, -4, -8, -12 and -16 bar) with three replications was conducted. There was no germination on -8, -12 and -16 bar, so these levels were omitted. The percentage of germinated seeds was recorded daily, and germination rate (1/D50) was calculated based on inversing the time taken to reach to 50% cumulative germination. To quantify the response of germination rate to temperature and to determine cardinal temperatures, physiological days and thermal time requirement for germination, Dent-like model was applied. Temperature, drought stress (-4 bar) and their interactions, had a significant influences on final germination percentage and germination rate of chickpea genotypes. The lower and higher temperature regimes than optimum, had more restrictive effects on germination traits in stress compared to non stress (0 bar) condition. There were considerable genetic variations among genotypes regarding to final germination percentage and germination rate. MCC.463 and MCC.873 genotypes had the highest final germination percentage both in stress and non stress conditions, but on these genotypes, germination rate was the highest only in non stress condition. Overall, mean and optimum temperature range for germination, were estimated 20-26oC, and it was the same in stress and non stress conditions. There were significant differences among genotypes for physiological days and thermal time requirement for germination, only in stress condition. Drought stress increased thermal time requirement for germination 2.8 times compared to non stress.

Severe varations of the weather condition can greatly affect crop yield. Many researches have been done to determine the role of different atmospheric variables on crop yield, from agrometeorological view point. These studies have resulted in relationships that are being used to predict the crop yield based on atmospheric data. In the present study, the effect of precipitation amount on rainfed wheat yield is studied at farm units in an eleven years period between 1992 to 2002 in the province of Ghazvin. The isohyte maps of the region is produced, based on the daily precipitation data from all the meteorological stations. The land-use map of the region is, then, used in the GIS environment to estimate precipitation amount in each farm unit of different cities of the province. Precipitation amounts during different stages of the growing season of wheat were also estimated. This resulted in 76 precipitation variables. The correlation between the rainfed wheat yield and verified 76 precipitation variables were tested. The results indicate that the precipitation variables which contain the total precipitation of the first six months of water year (October- March) and twenty days afterward, suggests the best correlation between the wheat yield and precipitation. Investigation shows that the variables which includes the total amount of precipitation during the first 6 month Agricultural year plus 20 days after make the highest correlation to demonstrate the variation of yield via precipitation.

Velvetleaf (Abutilon theophrasti Medic.) is one of the most important warm-season weeds in the field crops such as soybean. In order to determine the critical period of velvetleaf control in soybean field, an experiment was conducted in Gorgan in 2006 using a randomized complete block design with four replications. The experiments consisted of 2 series of treatments; the first set was control treatments that the crop was kept weed-free until the growth stages of 2 leaf, 4 leaf, 6 leaf stages, beginning bloom and beginning pod. The second set was interference treatments that velvetleaf was permitted to grow within the crop until the above-mentioned growth stages. Weedy and weed-free controls were also included in the study. The effects of control and interference treatments were significant on yield, height and maximum leaf area index of soybean and velvetleaf. Correlation between height, dry mater and maximum leaf area index of weed with yield of soybean were shown a negative linear relation. Using the Gompertz and Logistic equations, it was found that the critical period of controlling velvetleaf in soybean, considering 5% allowence decrease in yield, is between V2 (14 days after emergence or 239 CGDD) to V7 (43 days after emergence or 786 CGDD) leaf stages, while with 10% allowence decrease, is between V3 (18 days after emergence or 394 CGDD) to V5 (35 days after emergence or 616 CGDD) leaf stages.

In order to study the effects of microelements application and plant density on yield and morphological characteristics. A field experiment was carried out during 2005-2006 at the Research farm of the University of Tabriz. In this research, the effects of four plant densities (8, 12, 16 and 20 plants/m-2) and two microelement treatments (none spraying or spraying) on yield and essential oil production of peppermint were evaluated at two cuttings. These treatments were arranged in a factorial experiment on the bases of randomized complete block design (RCBD) with three replications and two-cutting analysis of compound variance (split plot on time).The results of first cutting showed that the foliar application of micro elements increased fresh and dry matter, essential oil yield, leaf area and percentage of green cover. Also' in the first cutting fresh and dry matter, green cover percentage and essential oil production increased by increasing plant density. In the second cutting, the foliar application of microelement, fresh and dry matter, leaf area and green cover percentage increased. The highest green cover percentage was observed in 20 plant s/m2. The results of two cutting indicated that peppermint plants grown better in first cutting than the second cutting. Plants harvested in first cutting had higher height, green cover percentage; fresh and dry yield and essential oil yield, but had lower bush and leaf essential oil.

Chickpea seed rot and seedling pre-emergence damping-off caused by Pythium ultimum is one of the most devastating diseases in Iran. Consequently, growers can expect as much as>80% reduction in stand and yield if measures are not taken to control the disease. The fungus used in this work was isolated from chickpea seeds, and identified as P. ultimum var. ultimum. It caused a 57.7 percent reduction of seed emergence in greenhouse trials. In the current study, the biocontrol potential of four antagonistic bacteria against the P. ultimum was evaluated. Pseudomonas fluorescens Qz29R, a well-known biocontrol agent obtained from the Washington State University, was comparatively used as a control. The performance of these bacteria was greatly influenced by different types of inoculation and their application methods. 95% if seeds coated with the biocontrol bacterium P. fluorescens isolate Pf-2 could considerably germinate in the prescenc of the P. ultimumin the plate assay. It appears to be a compatibility of bacterial treatments with metalaxyl, so that it may be applied in combination with the fungicide. Metalaxyl had no inhibitory effect on bacterial growth at different concentration used in this study. Captan inhibited the bacterial growth at the concentration of 10-3. In sterilized soil, metalaxyl was the most effective treatment, regarding theseedling stand and increased fresh weight of chickpeas. Isolate Pf-3 was considerably more effective than Pf-2, resulting in greater (P<0.05) seedling stand.

Determination of wetted soil diameter and depth and distributed humidity in different spaces to line source after irrigation is very important for drip irrigation designed. The flow regime moves in a line source under trickle irrigation in two dimensions (x, z). In this study, physical model was constructed and wetting front experiment were carried out in soils at deferent times with various discharge. The water content of soil was directly determined after each irrigation. By developing and simplification of Warrick, s equation to solvable and semi-analytical approximate equation, soil moisture was determined. Estimated moisture compared with the measured moisture and analyzed.The results were approximately the same as the measured data. This fact strengthened our views in this thesis which are developed are generally in wide range of soils.

The effect of exogenous silicon (Si) on the activity of the major antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD) in wheat (Triticum aestivum L.) under drought stress was investigated. Complete randomized design was performed with three treatments control, drought and silicon-drought (1 mmol silicate sodium kg-1) and three replications in the green-house. Result showed that compared to the plants treated with drought alone, Si treatment caused to increase the activity of CAT, SOD, APX, and POD and also the contents of photosynthetic pigments and soluble protein under drought stressed leaves. There was no significant difference in CAT activity between the drought and control treatments. Moreover, among the all studied enzymes, POD revealed the highest activity under silicon treatment. It is concluded that higher activity of antioxidant enzymes and isoenzymes electrophoretic banding patterns are depended to the silicon treatment. Moreover, Si causes to protect the plant tissues from oxidative damage under drought stress. The results of the present experiment coincided with the conclusion that Si may be involved in the metabolic or physiological changes to increase drought tolerance in wheat plant.

Soil structure could directly and indirectly affect soil water retention, hydraulic conductivity, aeration and temperature. It is also important in terms of soil mechanical impedance and nutrient diffusion in soil, which have impacts on plant growth and crop production. Many factors such as soil texture, organic matter and calcium carbonate content might change soil structural stability. The influences of these factors on aggregate stability were studied for 21 soil series from Hamadan province, Iran. Aggregate stability was measured using wet sieving method and mean weight diameter (MWD) of the aggregates was calculated. Three time durations of shaking (5, 10 and 15 min) in water were used to impose different hydromechanical stresses on soil aggregates. All of the measured intrinsic properties significantly affected structural stability. Short-time shaking (i.e. 5 min) resulted in better differentiation of soils on the basis of structural stability. This was due to the low intrinsic structural stability of aridic and semi-aridic soils in Iran. Among the intrinsic soil properties, soil organic matter had the most important role in aggregate stability. For instance, soil organic matter (OM) increased MWD of 5 min shaking (MWD5), 18 and 26 times greater than the clay and CaCO3 did, respectively. It could be predicted from the following regression equation: MWD5 (mm)=- 0.267+0.449 OM%+0.0245 Clay%+0.0169 CaCO3%       R2=84.8%Partial correlation analyses showed that the highest partial correlation coefficients were observed between MWD and soil clay content and then between MWD and OM for all of the shaking times.With increasing shaking duration, clay content effect on MWD increased but the influences of Organic Matter and CaCO3 contents decreased. Generally, the organic matter and clay contents were most important soil properties regarding aggregate stability for the studied soils. The short time (5 min) wet sieving may be recommended for structural stability assessment of the soils.

Efficacy of tillage and herbicide factors was studied in fallow during 2007-2008 in Islam abad in a Russian knapweed infested field. The experiment was done as split plot with two factors: tillage (two levels: with and without tillage) in main plot and herbicide (seven levels: 2, 4-D+MCPA, Triclopyre, glyphosate, 2, 4-D+MCPA+Triclopyre, 2, 4-D+MCPA, glyphosate, Triclopyre+glyphosate, and Bromicide) allocated to subplots. 30 days after spraying, biomass production in knapweed in control plots (without herbicide) for tillage and no tillage treatments was 381 and 693 g/m2, respectively. All herbicide treatments caused significant decrease in knapweed biomass.There was no significant difference amount herbicides treatment. Based on knapweed evaluation in wheat after fallow, 2, 4-D+MCPA, glyphosate, with 90% knapweed control) was the best treatment for this weed control. However, glyphosate, 2, 4-D+MCPA+Triclopyre, did not have significant difference with this treatment. All herbicide treatments caused significant increase in wheat seed yield.

In this study the PLRV transmission efficiency of five major genotypes of Scottish M. persicae) were analysed. The genotypes denoted as types A, B, C, J, and I. In virus transmission experiments detached leaves of PLRV-infected Physalis floridana and virus-free seedlings (2-3 leaf) of the same plant were used as virus source and test plant, respectively. Both acquisition and inoculation access periods were 3 days at 18oC with a 16 h photoperiod. One viruliferous aphid per seedling was used for inoculation and 24 seedlings for each genotype were inoculated. Three weeks after inoculation and based on symptoms or ELISA tests, the numbers of infected plants in each set of inoculated seedlings were determined. The transmission experiment was repeated five times. To reveal the factors underlying the differences in PLRV-transmitting abilities of the genotypes, transmission efficiency of PLRV and closely related virus, Beet mild yellowing virus (BMYV), by genotypes A and J were compared. Significant differences in PLRV transmission efficiency of the genotypes were observed. Genotypes A, B and C transmitted PLRV to more test plants. The comparison of the PLRV and the BMYV transmission efficiency showed that genotypes A and J transmitted BMYV almost with the same efficiency whereas genotype A transmitted PLRV more efficiently than did genotype J. These results suggest that such differences are likely to be caused by small variations within the aphid's receptors that recognize PLRV particles and assist their circulation and stability within the aphid's body. It has been shown that the genotypes A and B also carry all three known insecticide-resistance mechanisms and therefore can potentially increase the spread of PLRV.

In this study, clusters validity of several methods of cluster analysis based on different methods of data standardization and different distance criteria will be evaluated with discrimination function analysis. To reach the aim 7 inbred lines and 7 hybrids progenies of crossing between them and 4 open pollinated F1 hybrids were grown in an unbalanced grouped design with 3 replications and 22 agronomic characteristics were evaluated on genotypes. The discrimination function analysis showed that the Euclidean distance criterion was better than other distances criteria and a desirable clustering got based on it. Also, data standardization methods had same clustering and were better than data un-standardization. The dendrograms observation of several cluster analysis methods showed that the Unweighted Pair Group Method with Arithmetic (UPGMA), Complete linkage and Ward's minimum variance methods were better than the other methods. Also, the Fisher's linear discrimination analysis was fulfilled and it was observed that UPGMA, Complete linkage and Ward's minimum variance methods with performing valid clustering about 100% better than other methods could use of initial information of data and classified genotypes.

Water infiltration into the soil under different management conditions is very important in rangeland. In the present research, the effects of open grazing management and alfalfa cultivation on water infiltration into the soil was investigated in a part of Talesh mountainous rangeland comprises 500 ha. The infiltration was measured by the double ring infiltrometer in five replications in each area. Cumulative and instantaneous infiltration rate, minimum (infiltration capacity) and maximum instantaneous infiltration (peak infiltration) rates were compared in study treatments. The cumulative and instantaneous infiltration rates among replications and in two above-mentioned areas were then compared using ANOVA and paired sample t-test, respectively. The minimum and peak instantaneous infiltration rates were also compared using independent sample t-test in two aforesaid treatments. The results showed that there was a significant difference in final and peak instantaneous infiltration rates in two above-mentioned areas at the significant level of 1%, whereas no significant difference was found among replications. The final and the peak instantaneous infiltration rates in planted areas were found to be equal to 3.96 and 34.29 cm/h that represented a respective increase of 32% and 39% when compared with open grazing ones. The results of the present study verified the significant role of rangeland management in controlling water infiltration into the soil in the study area. Besides that, the necessity of proper rangeland management was also emphasized in order to access to suitable and stable hydrologic conditions in rangeland ecosystems.

The effects of different planting date including temperature and day length on developmental stages yield and yield components of four sunflower cultivars were studied in Kabotar Abad Expermental Station of Isfahan Agricultural Research Center in 1998 to 1999. Four cultivars (Zaria, Azargol, Golshid and Hysun 33) compared at four planting dates (May 5th and 26th, June 15th and July 16th) in a split plot design with four replications. The highest seed yield was obtained from the first planting date. Delay in planting due to change of temperature and day length caused faster development, earlier flowering and lower photosynthetic areas and these consequently lowered yield and yield components. Zaria with little difference to other genotypes was the latest mature cultivar. The cultivars under study varied significantly for vegetative characteristics and yield components. Zaria with the highest plant dry weight, head diameter and 1000-seed weight had the highest and Hysun 33 with the lowest plant dry weight, head diameter and 1000-seed weight produced the lowest seed yield. Planting date and cultivar interaction was significant for seed yield and the highest seed yield was obtained from Golshid in May 5th.

This experiment was conducted to determine the nutrient digestibilities during two consecutive years in warm and cold seasons (summer and winter). Eight Mehraban male sheep were used forin vivo study and complete random design (CRD) in factorial arrangement. The rations were modulated by alfalfa stem and barley grain (in 40, 50 and 70% levels). Chemical compositions were determined in feed and fecal. The feed residual and dry matter digestibility were measured in the summer and winter (warm and cold) seasons for two years. The data show that nutrient digestibilities were affected by year, season, ration and their interactions. In this term, protein and fiber digestibility were affected remarkably, while protein digestibility increased in cold season, crude fiber digestibility was reduced in this case. The adverse reflection was shown in warm season.The results of this study show that recommend the suitable feeding programe and housing conditions, more factors must be investigated in such experiment.

In order to Evaluate cheap and available substrates for oyster mushroom cultivation under rural conditions, three species of the mushrooms namely, Pleurotua florida, P. flabellatus and P. sajor-caju were grown on barley straw, lentil straw and rice bran under rural condition in spring, summer, autumn and winter seasons, adopting complete randomized block design with 9 treatments and 3 replications. Pure cultures of the mushrooms were grown and maintained on PDA medium.Spawns were prepared using boiled sterilized wheat seeds inoculated with pure culture of mushrooms. The substrates of mushroom production were chemically disinfected using carbendazim fungicide and formalin. All of the three mushrooms species yields good on barley and lentil straw in spring, summer and autumn cultivations, but the yields of rice bran substrate in all seasons were significantly lower than the other substrates. The highest yield (3600 g/ bag containing tow Kg of substrate) obtained from, P. flabellatus on lentil straw and the yield of P. florida on lentil and barley straw were 3321 and 2981 g/ bag, respectively in spring cultures. The yields of summer and autumn cultivation of the mushrooms were lower than the spring ones. The maximum yield of summer culture (2926 g/bag) obtained from P. flabellatus on lentil straw and the maximum autumn yield (3450 g/bag) recorded in P. florida on barley straw. The yields of winter cultivation were very much lower than that of the other season's yields. The highest yield of winter cultures (293 g/bag) recorded from P. flabellatus on barley straw which is far lower than other seasons yields. So, it is possible to economically grow the oyster mushrooms as an important low cholesterol protein source under rural condition on cheap and available substrates.